Anesthesiology

Anal Operations

What the Anesthesiologist Should Know before the Operative Procedure

Anorectal disorders affect about 4% to 5% of the adult population. The majority of anorectal conditions are treated surgically only if symptoms persist after a trial of conservative therapy. If patient selection and intraoperative and postoperative care are appropriate, most anal procedures can be performed on an outpatient basis.

What is the risk of delay in order to obtain additional preoperative information?

Patients should be optimized preoperatively prior to proceeding given that anorectal surgery is rarely emergent and infrequently urgent.

Emergent: Anorectal abscesses can lead to systemic sepsis and require immediate surgical drainage.

Urgent: Acute hemorrhoidal crisis is a rare event that results from acutely prolapsed, gangrenous, incarcerated, or thrombosed hemorrhoids. Treatment can range from observation to urgent surgery. Hemorrhage (primary or secondary) and paraproctitis are also considered acute cases.

Elective: The majority of anorectal diseases are operated on electively and include hemorrhoids, anorectal fistulas, anal condylomas, pilonidal sinuses, and anal fissures.

2. Preoperative evaluation

A careful pulmonary evaluation should be made preoperatively, especially given the unique positioning requirements for this surgery (jackknife prone, lithotomy, or lateral) and potential need for deep sedation, both of which can be challenging in the pulmonary cripple. Morbid obesity can also pose significant challenges to the anesthetic given impaired pulmonary mechanics (reduced FRC, increased V/Q mismatch) in this population. Routine cardiac clearance is generally not necessary given that anorectal surgery is considered a low-risk operation. That being said, a thorough history and physical exam should be performed on every patient to exclude unstable coronary conditions and allow for appropriate perioperative and postoperative risk stratification.

Delaying surgery may be indicated if: the patient’s medical conditions are not optimized and the disease could cause significant intraoperative or postoperative complications for the surgery.

3. What are the implications of co-existing disease on perioperative care?

The following sections on systems should each be considered in light of (1) perioperative evaluation and (2) perioperative risk reduction strategies.

b. Cardiovascular system

Perioperative evaluation

Acute/unstable conditions: According to the American College of Cardiology (ACC)/American Heart Association (AHA) 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery, a careful history should be obtained to ascertain serious cardiac conditions such as decompensated heart failure, unstable angina, recent myocardial infarction (MI), severe valvular disease, and significant arrhythmia. The presence of any of these conditions requires cancellation of the case and pursuit of further testing, cardiac consultation and/or intervention. There are few, if any, emergent anorectal conditions that would warrant proceeding without further evaluation.

Baseline coronary artery disease or cardiac dysfunction: Obtain a thorough history assessing the nature and severity of the disease including known diagnoses and past evaluations and whether it is optimized. This may involve questions about cardiac symptoms (chest pain, orthopnea, exercise tolerance, and dyspnea), changes in medications, recent interventions, and hospitalizations. Laboratory data including prior stress testing, catheterizations, echocardiography, chest radiography, and electrocardiography (ECG) should be reviewed prior to proceeding. According to the stepwise ACC/AHA algorithm, anorectal surgery falls into low-risk surgery. Therefore, unless these active cardiac conditions are present, further workup is not recommended. However, given the elective nature of the majority of these cases, it is important to use clinician judgment in high-risk patients and to recognize that the ACC/AHA guidelines are merely expert opinion recommendations, not standard of care.

Perioperative risk reduction strategies

Monitoring: The need for invasive monitoring including arterial, central venous, and pulmonary artery catheters generally depends on the disease severity and risks of placement. Given the short operative time, minimal blood loss, unlikely need for fluid resuscitation, and ability to perform many anorectal procedures under local anesthesia, invasive monitoring is rarely needed. It is important to anticipate potential hypotension with regional anesthesia and positions such as the prone jack-knife (secondary to blood pooling in the lower extremities resulting in decreased venous return), which may not be well tolerated in cardiac conditions such as aortic and mitral stenosis.

Goals: Maintain a balance between oxygen supply and demand to minimize the chance of myocardial ischemia.

Increase supply: (1) Increase oxygen content by avoiding hypoxia and anemia; can consider increasing FiO2 and transfusing blood if indicated. (2) Avoid tachycardia (affects supply and demand) because it can decrease diastolic filling time. Consider beta and calcium channel blockers. Premedication with anxiolytics and extreme care with laryngoscopy can assist in minimizing tachycardia. (3) Increase coronary perfusion pressure by increasing diastolic blood pressure (can use fluids and pressors) and decreasing left ventricular end-diastolic pressure (LVEDP) given LV coronary perfusion occurs primarily during diastole (right ventricular [RV] occurs in systole and diastole). Can also consider the use of nitrates, which dilate subendocardial vessels; however, care must be taken to not precipitate hypotension. Coronary artery diameter is an important determinant of coronary blood flow and may be adversely affected by acidosis and hypercarbia.

Decrease demand: (1) Avoid tachycardia, as above. (2) Decrease contractility. Can consider use of beta and calcium channel blockers. (3) Avoid increases in wall tension by optimizing preload and afterload. This includes judicious use of fluids and careful management of blood pressure. Poorly controlled hypertension should be treated preoperatively, especially given that this patient population is frequently chronically dehydrated, potentially worsening blood pressure lability after induction.

c. Pulmonary

Patients with pulmonary disease can pose a challenge with anorectal cases given the unique positioning and occasional need for deep sedation if a regional or local technique is employed.

Chronic obstructive pulmonary disease (COPD)

Perioperative evaluation: Perform a careful history to determine type and severity of COPD (chronic bronchitis versus emphysema). This includes a discussion of symptoms (cough, dyspnea, exercise tolerance), intubation history, oxygen use, recent hospitalizations, and medication history including current and past steroid use. Would also perform a thorough physical exam assessing for wheezing, rales, accessory muscle use, respiratory rate, clubbing, and signs of RV failure. In symptomatic or severe cases, a review of laboratory studies (chest radiographs, ECG, pulmonary function tests, ABGs, pulse oximetry, serum bicarbonate level) can be help determine if the patient is at risk for postoperative pulmonary complications (prolonged mechanical ventilation, reintubation, etc.).

Perioperative risk reduction strategies: Acute smoking cessation may lead to increased airway irritability; however, discontinuing greater than 6 to 8 weeks prior to surgery is beneficial. Identify and treat any underlying respiratory infections. Instruct patients to administer their aerosolized bronchodilators the morning of surgery. A regional technique may provide better pain control and minimize postoperative atelectasis by decreasing splinting, thereby allowing for more effective cough. It is important to recognize, however, that many COPD patients are dependent on active expiration; thus, a high thoracic motor block may impair pulmonary mechanics and predispose patients to aspiration. If a general anesthetic is used, optimize ventilation and oxygenation intraoperatively by prolonging expiratory times, slowing respiratory rate, increasing FiO2, adding PEEP, using bronchodilators, avoiding alkalosis, and humidifying gases. Consider avoiding nitrous oxide if there is bullous disease. Positioning can reduce vital capacity 12.5% in the jack-knife prone position and as much as 18% in the lithotomy position (see Ambulatory Anorectal Surgery). Therefore, careful monitoring of ventilation during positioning change is crucial in this patient population. Postoperatively, continue pulmonary toilet (nebulizers, Mucomyst, hydration, chest physiotherapy), encourage incentive spirometry, and ensure adequate pain control without oversedation.

Reactive airway disease (asthma)

Perioperative evaluation: History should be taken to determine disease severity including number of exacerbations, steroid use, hospitalizations, intubation history, and triggers (weather, exercise, anxiety). As with COPD, perform a physical examination assessing for wheezing and signs of infection. For elective surgery, consider delaying surgery if the patient is poorly optimized or has a recent respiratory tract infection as these can increase the risk of intraoperative bronchospasm.

Perioperative risk reduction strategies: Preoperatively, consider administering an aerosolized beta-2 agonist or anticholinergic agent. A regional technique may be beneficial to avoid airway manipulation. However, if sedation is used, care must be taken with light planes of anesthesia. If general anesthetic is used, would use inhalational agents that are more bronchodilating to the airway (sevoflurane vs. isoflurane) and avoid histamine-releasing agents such as morphine and atracurium. Also, would ensure patient is under a deep plane of anesthesia prior to intubation and incision to avoid triggering bronchospasm. In cases of severe asthma, a laryngeal mask airway (LMA) or mask should be considered to minimize airway manipulation, but may not be appropriate if the patient has a history of gastroesophageal reflex disease (GERD) or is to be in the prone position. If bronchospasm occurs intraoperatively, management includes deepening level of anesthesia with sevoflurane, and administering beta-2 agonists, ketamine, and small doses of epinephrine.

d. Renal-GI:

Patients are often dehydrated from preoperative mechanical bowel preparation.

Perioperative evaluation: Volume status should be carefully assessed for signs of fluid overload including pulmonary edema, hypertension, and congestive heart failure. Patients on dialysis should be operated on soon after to minimize electrolyte and volume disturbances. Hematologic abnormalities including chronic anemia are common in chronic renal failure (CRF) patients secondary to low erythropoietin. If a regional technique is being used, a platelet count should be obtained to exclude thrombocytopenia given that a qualitative platelet defect is likely present. Common metabolic disturbances are present in CRF patients, including hypocalcemia, hyperkalemia, hyperphosphatemia, hypoalbuminemia, metabolic acidosis, hypernatremia, and insulin resistance. A basic chemistry and electrolyte panel should be obtained prior to surgery.

Perioperative risk reduction strategies:Minimize administering known nephrotoxins (aminoglycosides, NSAIDs). Also, avoid anesthetics that are dependent on renal excretion, especially for short cases. A bowel preparation containing sodium phosphate may not be appropriate in patients with chronic renal insufficiency. Maintain renal perfusion by avoiding hypotension, which can decrease renal blood flow. For patients with a high likelihood of postoperative bleeding, consider having platelets and DDAVP available.

Gastrointestinal

Perioperative evaluation: A careful evaluation of the patient’s aspiration risk including history of reflux disease, hiatal hernia, and poor gastric emptying needs to be performed. Regional and local anesthesia usually require sedation; thus, these anesthetic modes do not necessarily decrease aspiration risk. Also, patient positioning (dorsal lithotomy and prone jack-knife) may also increase the risk of aspiration, especially if positive pressure is required through a face mask or LMA.

Perioperative risk reduction strategies: If symptoms are present, nonparticulate antacids, H2 antagonists, and metoclopramide followed by a rapid-sequence induction should be considered to minimize the risk and impact of an aspiration. Patients who are high risk for aspiration are not good candidates for deep MAC without control of the airway.

e. Neurologic:

Perioperative evaluation: A careful neurologic history should be performed to evaluate for cerebrovascular disease, spine pathology, intracranial aneurysm or tumor, and neuromuscular disorders. This includes evaluating for new-onset headache, uncontrolled seizures, history of syncope, transient ischemic attacks, and any focal neurologic signs such as weakness, visual disturbances, paresthesias, incontinence, dysphagia, tremor, and autonomic dysfunction.

Acute issues: Poorly controlled disease or onset of new symptoms requires evaluation and treatment prior to elective surgery. Chronic disease: In the case of cervical spine pathology, special care must be taken during positioning especially if the patient is prone under general anesthesia. Other considerations with prone positioning include avoiding pressure on the globe to prevent optic neuropathy and retinal artery occlusion. Patients with carotid disease undergoing surgery in the knee-chest position (exaggerated prone jack-knife with hips flexed and head more elevated) may potentially require a higher mean arterial blood pressure to maintain adequate cerebral perfusion pressure. A regional technique can be useful in these cases given the ability to monitor mental status; however, care must be taken with the sympathectomy that can follow spinal placement. Patients with chronic neuromuscular illness require a careful risk-benefit assessment prior to implementing any regional technique.

f. Endocrine:

N/A

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (e.g., musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

Immunologic: acquired immune deficiency syndrome

Perioperative evaluation: A thorough review of systems and drug therapy side effects (esophagitis, diarrhea, dysphagia, cardiomyopathy, and peripheral neuropathy) should be performed prior to induction. In addition, antiretroviral therapy may predispose these patients to pancytopenia and other laboratory abnormalities so baseline hematologic and electrolyte panels should be obtained.

Perioperative risk reduction strategies: Any upper GI symptoms need to be carefully assessed for prevention of pulmonary aspiration including need for premedication and rapid sequence induction. If the patient has a peripheral neuropathy related to their disease, it may be desirable to avoid regional anesthesia. Also, if the patient’s level of immune function is markedly attenuated, consider wound healing complications and possible infectious disease team consultation.

4. What are the patient's medications and how should they be managed in the perioperative period?

N/A

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

Anti-inflammatory medications: Perianal fistulas, anorectal abscesses and rectovaginal fistulas may be the result of inflammatory bowel disease such as Crohn’s and ulcerative colitis. Patients with Crohn’s disease are frequently on anti-inflammatory drugs such as sulfasalazine, mesalamine and corticosteroids. A careful review of systems must be performed given the numerous side effects of these medications including reflux, hypertension, type 2 diabetes, and an increased susceptibility to infections. Patients receiving long-term steroid therapy may be at risk for adrenal suppression and should be considered for a short perioperative stress dose depending on dose of steroid and extent of surgery.

Highly active antiretroviral therapy (HAART): Risk factors for perirectal abscesses and anal dysplasias include the immunocompromised patient (HIV and AIDS), many of whom are on HAART therapy. Antiretroviral medications impair the metabolism of multiple anesthetics and analgesics because of their effect on the cytochrome P450 isoenzyme; therefore, drug interactions must be reviewed preoperatively.

Antidiabetic agents: Diabetes is another risk factor for anorectal abscesses. Diabetic patients should withhold their morning dose of oral hypoglycemic agent such as metformin, glipizide, or Actos. Long-acting insulin preparations are usually taken at half the morning dose and short-acting insulin should be stopped. All patients should receive a blood sugar check prior to, intraoperatively (if brittle diabetic or >1-hour operation), and postoperatively and have a dextrose infusion running intraoperatively to avoid hypoglycemia.

i. What should be recommended with regard to continuation of medications taken chronically?

Cardiac: Beta blockers and all antihypertensive medications except diuretics should be taken in the usual doses until the day of surgery. Unless prescribed for congestive heart failure, consider holding angiotensin-converting enzyme (ACE)/angiotensin receptor blocker (ARB) therapy the morning of surgery, given associations of increased intraoperative hypotension requiring vasopressors. Patients on anticoagulants are usually asked to stop all antiplatelet therapy 1 week before surgery and Coumadin 5 days before surgery. For minor surgery, as is the case with anorectal surgery, this may not be required and a conversation should be initiated with the patient’s cardiologist, especially in the high risk patient.

Pulmonary: Continue preoperative beta agonists and bronchodilator therapy until the day of surgery. Depending on the severity and prior responses to treatment, nebulizers may be beneficial the morning of surgery.

Renal: Hold diuretics the day of surgery to avoid volume depletion.

Neurologic: Antiepileptics and Parkinson’s medications should be given the morning of surgery. Decisions regarding stopping versus continuing antiplatelet therapy in patients with cerebrovascular disease should be made with the assistance of the patient’s neurologist.

Antiplatelet: See cardiac recommendations. Also, the surgeon and provider should collaborate and weigh risks and benefits of stopping antiplatelet therapy, given that anorectal surgery is generally a minor procedure with minimal blood loss. All anticoagulants must be reviewed carefully by the anesthesiologist, especially if a regional technique is being considered.

Psychiatric: Antidepressants and anxiolytics should be continued perioperatively to avoid decompensation. Intraoperatively, care must be taken to avoid use of anesthetics that can interact poorly with these drugs. Demerol is contraindicated in patients on monoamine oxidase inhibitors (MAOIs) because of the risk of hypertension, convulsions, and coma. Tricyclic antidepressants can potentiate the effects of centrally acting anticholinergic drugs and indirect-acting vasopressors such as ephedrine.

All patients should be questioned about latex sensitivity and an allergy should be noted on the operative schedule. Fruits such as bananas, kiwis, chestnuts, and avocado may have cross-reactivity to latex; therefore, precautions should be taken in patients with allergic reactions to these food products. Possible sources of latex exposure in the operating room include gloves, tourniquets, medication vial stoppers, adhesive tape, nasal airways, blood pressure cuffs, Penrose drains, electrode pads, urinary catheters, and anesthesia reservoir bags. All latex-containing products should be removed from the operating room. Drugs should be drawn up in a manner such that latex contact is eliminated. Pretreatment with H2-blockers, steroids, and antihistamines does not necessarily protect a latex-allergic patient from anaphylaxis and therefore is not routinely performed. Rather, these medications and epinephrine should be available in the operating room should anaphylaxis occur.

l. Does the patient have any antibiotic allergies? (common antibiotic allergies and alternative antibiotics)

For penicillin-allergic patients, a combination of intravenous metronidazole and ciprofloxacin is often used. Patients with a known history of MRSA may require intravenous vancomycin.

m. Does the patient have a history of allergy to anesthesia?

Malignant hyperthermia (MH)

Documented: Avoid all triggering agents such as succinylcholine and halogenated inhalational agents. Follow a proposed general anesthetic plan: If regional or local is not appropriate, a nontriggering general anesthetic technique such as total intravenous anesthesia can be used. Even though all intravenous anesthetics are safe, tachycardia-producing drugs such as ketamine and pancuronium can confuse the diagnosis and should be avoided. If a muscle relaxant is needed, nondepolarizing agents can be administered. To ensure a clean anesthetic machine, oxygen should be run at 10 L/min for 20 minutes and all tubing, circuit, bag, and absorber should be replaced. Ensure MH cart is available: Dantrolene should be easily accessible but prophylaxis is not recommended.

Family history or risk factors for MH: MH produces a hypermetabolic state that can be life-threatening. Given the ability to avoid triggers easily, all of the above precautions should be used in patients with a questionable history or risk factors for MH (positive family history, history of central core disease, myopathy, or Duchenne’s muscular dystrophy).

Local anesthetics/muscle relaxants

Allergic reactions to local anesthetics are rare and usually involve an ester agent. Amides do not cross-react with esters; therefore, a patient allergic to one class can be substituted a drug in another. Neuromuscular blocking agents play a dominant role in producing severe IgE-mediated allergic reactions. Cross-reactivity to neuromuscular blockers has been reported; therefore, any suspected hypersensitivity reaction should be investigated preoperatively and postoperatively.

5. What laboratory tests should be obtained and has everything been reviewed?

Given that anorectal surgery is considered a low-risk procedure, in the healthy patient, no preoperative laboratory testing, imaging, or studies are necessary.

Common laboratory normal values will be same for all procedures, with a difference by age and gender.

Hemoglobin levels: The incidence of significant blood loss in anorectal surgery is quite low; therefore, routine ordering of preoperative hemoglobin is generally not indicated. Consider hemoglobin measurement in high-risk populations such as those with a history of bleeding, malignancy, recent chemotherapy or radiotherapy, chronic severe illness, or clinical findings suggestive of anemia. A type and screen is not necessary given estimated blood loss is usually <100 mL.

Electrolytes: Check in patients on diuretics, digoxin, ACE inhibitors, ARBs, or steroid therapy; those with a history of renal dysfunction, and those with recent IV contrast exposure.

Coagulation panel: Consider obtaining in those with a personal or family history of bleeding diathesis, patients on anticoagulation, severely malnourished patients, alcoholics, and those with a history of severe liver disease.

Blood glucose: Consider checking in patients who have risk factors such as obesity, presence of a strong family history of diabetes, or history of steroid use.

Imaging studies: Chest radiographs should be considered in patients with a history of congestive heart failure or renal disease and those who present with new or worsening pulmonary symptoms. The ACC/AHA 2007 guidelines do not recommend obtaining an ECG in asymptomatic patients undergoing low-risk procedures such as anorectal surgery. ECGs should be obtained in symptomatic patients and can be considered in those with cardiac risk factors such as ischemic heart disease, compensated or prior heart failure, diabetes, renal insufficiency, and cerebrovascular disease.

Other tests: Pregnancy test should be obtained if there is a suspicion of pregnancy (no form of birth control, unreliable history, etc.).

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

The procedure can be performed under general anesthesia, regional anesthesia (spinal, epidural, combined spinal-epidural), or local perianal nerve block with or without sedation.

Regional anesthesia

Regional anesthesia can be performed with monitored anesthesia care (MAC) or, more rarely, general anesthesia. The goal is to provide a segmental block guided by the extent and location of the operation. Extensive traction and manipulation of the rectum will require a T10 level, whereas the majority of procedures outside of the anal canal will only require the S2-S4 nerve roots distribution to be anesthetized. Because of this, the technique most commonly used involves a spinal sacral block. This can be performed by the injection of small doses of hyperbaric bupivacaine (1mL 0.5%) or hyperbaric ropivacaine (1.5mL 1%) into the subarachnoid L3-L4 space followed by sitting up the patient to ensure adequate sensory “saddle” coverage and prevent cephalad spread of block. Hypobaric spinal blocks can be used for patients in the jack-knife or knee-elbow position. An advantage to this technique includes minimal incidence of motor blockade in the lower limbs.

Benefits:There is a lower incidence of nausea and vomiting even when compared to use of a TIVA (total intravenous anesthesia) technique. Airway-related complications such as sore throat, aspiration, airway trauma, hypoxemia, and laryngospasm are avoided. The patient is able to communicate with the operative room personnel during the procedure. There is improved postoperative pain control including lower analgesic consumption within 24 hours after surgery. The ability to position the patient awake minimizes brachial plexus nerve palsies, cervical strain, and ocular injuries. Of course, care still needs to be taken with peroneal nerve injury (lithotomy position), genital pressure, and groin trauma (jack-knife prone position).

Drawbacks: This is contraindicated or limited in patients taking clopidegrol, warfarin, or other anticoagulants; thus, ASRA guidelines need to be followed with regard to holding/restarting these drugs. Also, if the patient’s systemic disease is severe, contact patient’s cardiologist/neurologist/primary care physician with regard to risk of holding these medications. Positioning on the table (jack-knife, prone, lithotomy) may be uncomfortable or anxiety-provoking for the patient and require deep sedation or general anesthesia to tolerate it. Sympathectomy may not be tolerated in patients with valvular lesions, severe coronary artery disease, or cerebrovascular disease. Occasionally, there is a need for additional procedures or inadequate block requiring conversion to general anesthesia or supplementation with local anesthesia by the surgeon.

Postdural puncture headache (PDPH) is a known complication of spinal anesthesia, the rate of which depends on multiple factors including needle gauge, use of an atraumatic needle, and age of the patient. Compared by Schmittner and colleagues, the use of Quincke cutting needles, even in a smaller gauge, led to a considerably higher rate of PDPH than did use of the larger noncutting spinal needles.

General anesthesia (LMA versus ETT)

Benefits: Provides a secure airway and ability to adjust ventilation including use of positive pressure ventilation and PEEP. Also provides a rapid onset and easily adjustable depth of anesthesia. Can be used in patients with altered mental status including dementia or delirium May be better tolerated in patients who may have difficulty with positioning awake (jack-knife prone, lithotomy, or lateral decubitus).

Drawbacks:If an LMA is used, proper seating and ventilation can sometimes be challenging given the positioning requiring initial or midway conversion to an ETT. Laryngospasm may occur in patients under light planes of anesthesia, especially with anal dilation. While positioning the asleep patient in the prone position, care must be taken to avoid ear and ocular pressure trauma, brachial plexus stretch, chest wall trauma secondary to support bolsters, and genital injury. Postoperative period can be complicated with nausea and vomiting secondary to effects of inhaled anesthetics and intravenous opioids. Postoperative myalgias may occur if succinylcholine is used as a muscle relaxant.

Local perianal nerve block

This has been used as the sole anesthetic with or without sedation as well as in conjunction with general and regional anesthesia for postoperative pain management. MAC is not an option as the sole anesthetic given the intensity of pain with anal retraction. Several infiltration techniques into the anal sphincter and perianal skin have been described and include posterior ischiorectal fossa infiltration to block the nerves that pass through the fossa, and perisphincteric deposition extending to the levator to block the terminal nerve branches of the inferior hemorrhoidal, internal pudendal, and anococcygeal nerves. Block onset can be as quick as 2 to 5 minutes as anal sphincter relaxation occurs and enables painless insertion of the anal retractor.

Benefits: Can be used as sole method of anesthesia, for most anal surgeries that surgeons can safely perform on their own, including emergent open hemorrhoidectomies, anocutaneous fistulectomies, and sphincterectomies. Easy surgical skill level, quick to perform, and fast in onset, and can provide postoperative pain relief for as long as 12 hours. Epinephrine added to the local anesthetic can produce local vasoconstriction and may reduce operative blood loss. May be able to avoid complications of general or spinal anesthesia including nausea, vomiting, and headache. Several studies suggest lower turnover times between cases and shorter PACU recovery time, ultimately reducing time spent in the hospital and thus hospital cost.

Drawbacks: Can have an incomplete block with need for local supplementation or conversion to general anesthesia. Patient anxiety about the procedure or pain with local injection may require deliverance of a significant amount of intraoperative sedation, which may be lead to hypoventilation and hypoxia. Airway problems and pulmonary complications can be especially challenging to manage given positioning of the procedure (jack-knife prone, lithotomy). Other complications observed related to perianal blocks in two recent studies included small hematomas, bleeding, and abscess formation at the local infiltration site. In a few studies, patient satisfaction was lower when this technique was compared with regional secondary to poorer postoperative analgesia and pain on injection.

6. What is the author's preferred method of anesthesia technique and why?

Perianal nerve blocks with MAC would be our preferred method of anesthesia given the low incidence of side effects such as urinary retention, backache, headache, residual motor blockade, sore throat, drowsiness, nausea, vomiting, and potential faster discharge time for outpatient procedures. Although successfully performed at numerous ambulatory centers and shown to be effective for the majority of anorectal procedures, this method depends highly on patient cooperation, operator skill, and appropriate case and patient selection for success. Currently there are varied methods of performing the block and local techniques have not yet been standardized.

Some surgeons do not like this technique because of anatomical distortion that may occur with injection. Also, an adequate block may be difficult to achieve in long procedures, those entering the peritoneal cavity (high fistulas, deep rectal polyps), or those in which there is an inflammatory process leading to increased acidity of the tissues (perirectal abscesses). Finally, multiple local anesthetic injections into the vascularized anorectal zone can be highly painful, necessitating deep sedation. Patients with a high aspiration risk, pulmonary dysfunction or a potentially difficult airway may not be appropriate candidates for this technique.

It is unclear whether or not antibiotic prophylaxis reduces the chance of postoperative wound infection in hemorrhoidectomy. A recent multi-institutional large retrospective database review by Nelson reported postoperative surgical site infection as an extremely rare event, with a rate of 1.4%, potentially rendering prophylactic antibiotics unnecessary. Nevertheless, given the fecal flora associated with anal wounds, antibiotic therapy is still routinely used.

Antibiotics used in the current literature prior to anal surgery include cefazolin or a second-generation cephalosporin such as cefoxitin for greater gram-negative coverage. These should be given within 60 minutes prior to incision and repeated at 1 to 2 half-lives. Of course, prior to administration, updates in local and national recommendations should be reviewed and drug selection modified if appropriate.

Types of surgical procedures

Anorectal abscess: Treatment usually involves prompt surgical drainage. Given local inflammation, increased acidity, and exquisite tenderness on exam, a perianal nerve block may not be well tolerated or as effective as regional or general anesthesia.

Anal fistula: Treatment involves determining the anatomic course of the fistula and ablating all secondary tracts. An exam under anesthesia is performed to determine depth and route of the fistula. Although many can be performed under local, because the etiology is not known, surgical exploration may be better served by regional or general anesthesia. Occasionally diluted methylene blue dye may be injected into a fistula to trace its path.

Intraoperative care

Communicating with the surgeon in timing deep sedation (boluses of propofol, fentanyl) to the perianal local infiltration may reduce chance of hypoventilation and pain on injection. Gentle intraoperative fluid resuscitation minimizes postoperative urinary retention.

Most common intraoperative complications

Pulmonary complications: Procedures done under general anesthesia in the prone or jack-knife position may need to be intubated for airway control. A laryngeal mask airway may be used; however, appropriate patient selection is critical. Patients who have decreased pulmonary reserve may not tolerate spontaneous ventilation in these positions. In addition, aspiration and laryngospasm are at increased risk using this technique. If a MAC is used with a regional or local nerve block method, care must be taken to slowly titrate desired level of sedation. Oversedation can lead to apnea and subsequent hypoxia which can be difficult to manage in the prone position. In case of urgent/emergent need for airway control, a stretcher should always be easily accessible to turn patients supine.

Hypotension: Risk factors for this discussed in the literature include block height T5 or greater, age 40 years or older, baseline systolic blood pressure less than 120, and spinal placement above L3-L4. In the jack-knife prone position, more profound hypotension can be seen due to blood pooling and impairment of venous return. Given existing data on increased urinary retention in the setting of large preoperative and intraoperative fluid administration, would recommend use of vasopressors along with small boluses of fluid to treat this problem.

a. Neurologic:

N/A

b. If the patient is intubated, are there any special criteria for extubation?

Although extubation can be performed in the prone position, patient selection is important given that airway complications such as obstruction, aspiration, and laryngospasm may ultimately require mask ventilation and/or reintubation.

c. Postoperative management

A multimodal approach should be employed using a combination of intravenous or oral opioids with adjuncts like acetaminophen and NSAIDs. Alternatively, if a regional technique like epidural or spinal anesthesia is employed, the addition of adjuvants like clonidine has been shown to provide greater and extended analgesia. Neuraxial opioids may be appropriate but require respiratory monitoring. Transdermal fentanyl may be effective in patients with chronic pain. Regardless of technique chosen, perianal infiltration of a long-acting local anesthetic should be performed intraoperatively for postoperative pain relief. Adjuncts like dexmedetomidine to perianal blocks may have an additive effect in postoperative pain control.

Anorectal surgery is being increasingly performed in an ambulatory manner given the overall low anesthetic and surgical complication rates. Suggested benefits of day surgery include increased patient comfort at home, lower rate of nosocomial infections, and reduced health expenditures.

Common postoperative complications

Postoperative urinary retention is the most common complication and reported as high as 50%. The exact etiology is unclear, but detrusor muscle inhibition and urethral spasm secondary to pain have both been implicated. Neuraxial opiates and long-acting local anesthetics (bupivacaine versus ropivacaine) have been associated with increased urinary retention. Toyonaga et al. concluded that in addition to female sex and postoperative pain, perioperative administration of more than 1000 mL of fluid was an independent risk factor for urinary retention after anal fistula surgery. They also showed that fluid restriction led to less urinary retention. Additionally, Keita et al. found that patients older than 50 years, patients with bladder volumes of 270 mL or more on arrival to the PACU, and those who received 750 mL or more of intraoperative fluids were at increased risk for urinary retention. Treatment includes intermittent sterile catheterization to prevent detrusor muscle injury and urinary tract infection.

Because of the extensive innervation of the anal canal, postoperative pain can be severe and is a common disturbance after anorectal surgery. It can lead to difficulty with defecation and increased urinary retention. Treatment by the oral route should use a multimodal approach including NSAIDs and acetaminophen as adjuncts to low dose opioids or weak mu agonists such as tramadol. Tramadol, unlike other opioids, has no clinically relevant effect on respiratory parameters and has a reduced rate of constipation. Warm sitz baths can provide pain relief and increase local blood circulation. Topical ointments like cholestyramine and sucralfate may provide a local pain-reducing effect. Ketorolac administered before anorectal surgery either intravenously or as part of the local anesthetic mixture, has been shown to improve postoperative pain control and quality of recovery.

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